The present invention relates to punch presses using a punching tool set which can be readily changed by machine controlled movement of the punch and die from a tool storage area which is a part of the press assembly.
Punch presses are widely employed for producing cutouts of various shapes in workpieces. In a nibbling machine, the punch tooling is operated repetitively as the workpiece is being moved through the work station to produce a large cutout of a desired contour. As used herein, the term "punch press" includes presses which punch holes at spaced apart locations in the workpiece and nibbling type punch presses which move the workpiece under the punch to effect punching at contiguous positions to cut an extended contour.
Although there are manually operated punch presses wherein the operator moves the workpiece on the support table relative to the work station, most modern or high volume punch presses include an X-Y coordinate guide system and numeric control system to clamp and move the workpiece automatically in accordance with a predetermined program. Moreover, since many are intended to produce cutouts of various sizes and configurations, magazines of various types have been provided to carry a multiplicity of sets of punch and die tooling for use at the work station.
There are a number of versions of such punch presses which use tool holders providing interchangeable tool sets since processing a piece in a modern plant may require the use of a number of tool sets, one after another. As soon as one tool set has finished its action, it is exchanged for a second, and then a third, etc. When the workpiece has been fully processed, the operator may start punching the next workpiece, starting again with the first tool set.
In some punch presses and nibbling machines, the cooperating punch and die tooling is respectively carried in upper and lower turrets which rotate the tooling into the operative work station position. One of the turrets is located below the support plane of the workpiece and the other is located thereabove; and the ram strikes the punch to drive it downwardly within the upper turret against the workpiece and into the die which is supported in the lower turret. As will be appreciated, such turret-type magazines occupy a substantial amount of space and impede access of the operator to portions of the press.
In most tool changer punch presses, the tooling is stored in a tool storage assembly at the front of the frame, and a transfer mechanism is provided to move the desired tooling therefrom into forwardly facing passages in the tool holding elements on the ram and die holder. Such tool changer type presses have the advantage of effecting firm coupling of the punch to the ram, and positive support for the die below the workpiece. A particularly advantageous type of tool storage and transfer assembly at the front of the press for a compact punch press is illustrated and described in Klingel U.S. Pat. No. 4,719,691 granted Jan. 19, 1988.
In Erlenmaier U.S. Pat. No. 4,951,375 granted Aug. 28, 1990, there is illustrated and described a punch press in which tool sets are carried on the horizontal rail of the workpiece guidance system and the tool sets are moved thereby through rearwardly facing passages into the tool holding elements on the ram and die holder.
In both of these types of tool changer assemblies, there are physical limitations on the number of tool sets which are stored. Accordingly, installations which require a greater number of tool sets to process workpieces have frequently employed robots to move tools to and from large tool storage racks adjacent the punch press. Such assemblies tend to be costly and may often greater programming skill.
It is an object of the present invention to provide a novel press in which tool feeding to, and removal from, the tool mounting assemblies of the ram and die holder may be effected automatically from two discrete storage areas in the press.
It is also an object to provide such a press in which the tool sets in the punching station may be exchanged rapidly while the workpiece remains on the work support table and clamped in the guidance system.